How does the brain categorize objects? Where is this information stored? Mostly, it's thought that the ventral stream of the visual system codes for object identity. Neuronal activity in the lateral prefrontal cortex has been related to stimulus categorizaton (Freedman et al., 2001). However, a newly published paper reports that after training in a categorization task, neurons in the parietal lobe of macaque monkeys became sensitive to category information.

Scientists have pinned down the region of the brain that encodes the category or meaning of visual information.

[NOTE:Wow! Really?? Can I write for LiveScience.com?]

The ability to take a piece of information through our senses, assign meaning to it and categorize it helps people make sense of the world around them and behave accordingly. Because of this, when a chair is seen by the eyes, it's deemed appropriate for sitting on.

"You're not born knowing about categories or things like chairs or tables or telephones," said lead author David Freedman, a postdoctoral research fellow in neurobiology at Harvard Medical School. "Instead those develop through learning." [NOTE:no kidding!!]

What I see is what I amAnd I see before me an impoverished man

I am what I see

--ibid

. . .

"The activity didn't just encode what those visual patterns looked like," Freedman said. "Instead, the activity encoded what those patterns actually meant or what category those patterns belonged to."

Of course, the reality of the experimental conditions was a lot more complicated than you're led to believe by the popular press (and by the first author's soundbyte). The "categories" were determined by direction of motion, and the specific parietal lobe region in question here is the lateral intraparietal (LIP) area. So it's not as if, suddenly, everything you knew about object recognition was wrong.

Categorization is a process by which the brain assigns meaning to sensory stimuli. Through experience, we learn to group stimuli into categories, such as 'chair', 'table' and 'vehicle', which are critical for rapidly and appropriately selecting behavioural responses. Although much is known about the neural representation of simple visual stimulus features (for example, orientation, direction and colour), relatively little is known about how the brain learns and encodes the meaning of stimuli. We trained monkeys to classify 360° of visual motion directions into two discrete categories, and compared neuronal activity in the lateral intraparietal (LIP) and middle temporal (MT) areas, two interconnected brain regions known to be involved in visual motion processing. Here we show that neurons in LIP—an area known to be centrally involved in visuo-spatial attention, motor planning, and decision-making -— robustly reflect the category of motion direction as a result of learning. The activity of LIP neurons encoded directions of motion according to their category membership, and that encoding shifted after the monkeys were retrained to group the same stimuli into two new categories. In contrast, neurons in area MT were strongly direction selective but carried little, if any, explicit category information. This indicates that LIP might be an important nexus for the transformation of visual direction selectivity to more abstract representations that encode the behavioural relevance, or meaning, of stimuli.

The Harvard press release is also guilty of duping the reader into thinking that parietal cortex is responsible for encoding the meaning of familiar visual images.

Boston, MA -- Socks in the sock drawer, shirts in the shirt drawer, the time-honored lessons of helping organize one's clothes learned in youth. But what parts of the brain are used to encode such categories as socks, shirts or any other item, and how does such learning take place?

New research from Harvard Medical School (HMS) investigators has identified an area of the brain where such memories are found. They report in the advanced online Nature that they have identified neurons that assist in categorizing visual stimuli. They found that the activity of neurons in a part of the brain called the parietal cortex encode the category, or meaning, of familiar visual images and that brain activity patterns changed dramatically as a result of learning. Their results suggest that categories are encoded by the activity of individual neurons (brain cells) and that the parietal cortex is a part of the brain circuitry that learns and recognizes the meaning of the things that we see.. . .

Freedman is optimistic that research of this type will eventually contribute to a better understanding of neurological diseases and disorders. "Understanding how the brain learns, stores, recognizes and recalls visual information will help us overcome impairments to these functions caused from brain damage and diseases, including strokes, Alzheimer's disease, and schizophrenia," Freedman says.

[NOTE:And this rose-colored phrasing will help them get press coverage and grant funding.]

Last week, a reclusive Russian topologist named Grigory Perelman seemed to be playing to type, or stereotype, when he refused to accept the highest honor in mathematics, the Fields Medal, for work pointing toward the solution of Poincaré’s conjecture, a longstanding hypothesis involving the deep structure of three-dimensional objects. He left open the possibility that he would also spurn a $1 million prize from the Clay Mathematics Institute in Cambridge, Mass.

... It was not so much a medal that he was rejecting but the idea that in the search for nature’s secrets the discoverer is more important than the discovery.

"I do not think anything that I say can be of the slightest public interest," Perelman said. ... "I know that self-promotion happens a lot and if people want to do that, good luck to them, but I do not regard it as a positive thing.". . .

...What matters are the ideas, not the brains in which they alight. Posted without fear of thievery on the Internet beginning in 2002, his proof, consisting of three dense papers, gives glimpses of a world of pure thought that few will ever know.. . .

It has taken nearly four years for Dr. Perelman’s colleagues to unpack the implications of his 68-page exposition, which is so oblique that it doesn’t actually mention the conjecture. The Clay Institute Web site carries links to three papers by others — 992 pages in total — either explicating the proof or trying to absorb it as a detail of their own.

...Camus' story line is ripe for geopolitical literary misinterpretation. The main character, Meursault, spends much of his life as the young George Bush did, engaging in escapades that demonstrate little drive or motivation. On a visit to the beach with friends, he gets into a fight with some Arabs. Later, he finds one of the Arabs and without much further provocation shoots him repeatedly. During the circus-trial that follows, and the long hours Meursault spends in jail, he is remorseless and unable to engage in contemplation. On the day of his execution, he has a flickering thought that he might have lived another life. But mostly he's excited about the day and hopes that everyone will cheer for his death.

Thursday, August 24, 2006

This undated photo released by the International Mathematician Congress shows Grigori Perelman, from Russia, who was awarded with a prestigious Fields Medal at the International Congress of Mathematicians in Madrid, Tuesday, Aug. 22, 2006. Perelman, a reclusive Russian genius who says he's cracked one of history's toughest math problems won the equivalent of a Nobel prize Tuesday, but refused to accept it -- a stunning renunciation of accolades from the top minds in his field. Perelman, a 40-year-old native of St. Petersburg, was praised for work that might help scientists figure out the shape of the universe. But besides shunning the medal, colleagues say he also seems uninterested in a separate, million-dollar prize he might be due over his feat of wizardry: proving a theorem about the nature of multidimensional space that has stumped very smart people for 100 years.

Far fewer Vietnam veterans suffered from post-traumatic stress as a result of their wartime service than previously thought, researchers are reporting today, in a finding that could have lasting consequences for the understanding of combat stress, as well as for the estimates of the mental health fallout from the Iraq war.

The report, published in the journal Science and viewed by experts as authoritative, found that 18.7 percent of Vietnam veterans developed a diagnosable stress disorder that could be linked to a war event at some point in their lives, well under the previous benchmark number of 30.9 percent. And while the earlier analysis found that for 15.2 percent of the veterans the symptoms continued to be disabling at the time they were examined, the new study put that figure at 9.1 percent.

But before mentioning the Science article, I must point out two more gems in the current NYT:

And in the fall “The Architecture of Happiness,” by the philosopher Alain de Botton, who lives in England, will be published in the United States. In it he argues that physical environment is a crucial contributor to well-being. Like it or not, he suggests, the spaces we live in shape our sense of happiness and of self, so we had better choose them carefully.

Even before this vogue took hold in America, however, a number of influential East Coast decorators were exploring the same issues, and advancing a theory of their own: that a maximalist, color-saturated approach to interiors is a secret to happiness — maybe even the secret.

“Your home should be like a good dose of Zoloft,” Jonathan Adler, the ceramist and decorator, and one of the most prominent members of this group, wrote in his 2005 book, “My Prescription for Anti-Depressive Living.”

Growing up in poverty is associated with reduced cognitive achievement as measured by standardized intelligence tests, but little is known about the underlying neurocognitive systems responsible for this effect. We administered a battery of tasks designed to tax specific neurocognitive systems to healthy low and middle SES children screened for medical history and matched for age, gender and ethnicity. Higher SES was associated with better performance on the tasks, as expected, but the SES disparity was significantly nonuniform across neurocognitive systems. Pronounced differences were found in Left perisylvian/Language and Medial temporal/Memory systems, along with significant differences in Lateral/Prefrontal/Working memory and Anterior cingulate/Cognitive control and smaller, nonsignificant differences in Occipitotemporal/Pattern vision and Parietal/Spatial cognition.

The topic is mulitifaceted, controversial, and difficult to study without rasing a ruckus. With the mere mention of such a question,

How and why might a sociological construct, SES, be associated with brain function?

the media (and assorted pundits) raise the big red flags of genetic determinism and racial stratification (both pro and con). Fortunately, Farah and her colleagues are keenly aware of the Neuroethics involved in such a research enterprise, so they are not blindly stumbling into this line of work without an awareness of its social implications.

Some scientists plead ignorance of the controversy their work may inspire. Others are blatantly open about their xenophobic agendas. Among the worst offenders in the latter camp is J.P. Rushton, who published a paper that correlated measurements of hat size in military recruits with race, sex, and I.Q.

The issue of whether human populations differ in brain size remains controversial. Cranial capacities were calculated from external head measurements reported for a stratified random sample of 6,325 U.S. Army personnel measured in 1988. After adjusting for the effects of stature and weight, and then, sex, rank, or race, the cranial capacity of men averaged 1,442 and women 1,332 cm3; that of officers averaged 1,393 and enlisted personnel 1,375 cm3; and that of Mongoloids averaged 1,416, Caucasoids 1,380, and Negroids 1,359 cm3.

It's kind of laughable that someone who has attracted so much media attention is the first to cry censorship...

And he's joined forces with that other paragon of complete genetic determinism, Arthur Jensen.

Despite repeated claims to the contrary, there has been no narrowing of the 15- to 18-point average IQ difference between Blacks and Whites (1.1 standard deviations); the differences are as large today as they were when first measured nearly 100 years ago. They, and the concomitant difference in standard of living, level of education, and related phenomena, lie in factors that are largely heritable, not cultural. The IQ differences are attributable to differences in brain size more than to racism, stereotype threat, item selection on tests, and all the other suggestions given by the commentators. It is time to meet reality. It is time to stop committing the "moralistic fallacy" that good science must conform to approved outcomes.

Hmm, what was the original topic of this post? Oh yeah, SES and brain development. Back to a more nuanced view (Farah et al., 2006).

Although SES is generally estimated by measuring parental education and occupational status, it encompasses far more than these simple indices, including associated differences in physical and mental health (Adler et al., 1994) and in physical and psychosocial aspects of the environment (Evans, 2004). Important psychosocial factors include the presence of both parents in the home and parental stress and depression. Physical factors include nutrition and exposure to pollutants. Any of these is, in principle, capable of influencing brain development and function. In addition, some of the variance in an individual's SES has been attributed to genetic factors (Lichenstein and Pederson, 1997), which could also be manifest in the brain.

The study used an extensive testing battery to assess different (purported) aspects of neurocognitive functioning. The authors relied on other neuroimaging studies to make an approximation between each cognitive test and a major brain region recruited to perform it. The participants were 30 low SES African American children and 30 middle SES African American children. The results are shown in Fig. 1 below.

There were significant differences between the groups on tests of language (left perisylvian), working memory (lateral prefrontal), cognitive control (anterior cingulate), and memory (medial temporal), but not for reward processing (ventromedial prefrontal), spatial cognition (parietal), or visual cognition (occipitotemporal). The authors state that

...cognitive ability is not depressed across the board among children of low SES. Rather, abilities that have been linked to specific neurocognitive systems are disproportionately affected.

Has anyone seen this experiment covered in the popular press? Of course not, because it admits that there are complicated and multifactorial reasons for such an outcome -- not amenable to an easy soundbyte!

The present study was not intended to identify the causes of the SES disparities found here. Given the complex nature of SES and its correlates, the list of possible causes is long, including: physical health factors such as prenatal care, nutrition and lead exposure; psychological factors such as stress, parental availability and childrearing practices; and genetic factors. Previous studies of SES disparities in cognitive development have either measured none or at most a few of these factors.

Furthermore,

A common misunderstanding regarding the neural bases of cognitive phenomena is that neural bases imply genetic bases.

SUMMARY from The Neurocritic: By merely recognizing the complexity of how SES may influence cognitive achievement, the authors have advanced the field of neurocognitive development.

If febrile convulsions can confer benefits to learning and memory, then might other neurological disorders offer similar cognitive enhancement? As it turns out, an article in the newest issue of the Journal of Cognitive Neuroscience speaks to this very question, and turns up some fascinating results.

A comparison of the genomes of neanderthals and humans will not, of course, highlight any anatomical or functional differences between the human and neanderthal brain. It will, though, hopefully shed more light on the molecular events underlying evolution of the human brain, which in turn may allow researchers to infer more about the differences in the brains of the two species.

Legal battles often revolve around unsubstantiated claims that cannot be proven by hard evidence. In legal cases, No Lie MRI's evidence will allow objective, scientific, mental evidence, similar to the role in which DNA biological identification evidence is used.

Really?? Just like DNA? And this:

Investors discount future cash flows, resulting in lower perceived net present values of possible investments due to the potential of deception from unverifiable claims made by corporate officers of potential investment. These corporate officers could receive higher valuation of the potential investment by lowering the risk to the potential investors. No Lie MRI, Inc. increases value from reducing risk through mental verification.

Thursday, August 10, 2006

I must point out an excellent series of posts at Language Log that closely examines a few of the shaky claims made in the new book by Louann Brizendine, The Female Brain. Oh, you've read about the book in the popular press and in Neurobloggy Land. Sandra at Omni Brain has the best description of a different Female Brain assumption:

I could maybe buy into the Lear jet theory [analogy to a small airfield for women's thoughts about sex, but to O'Hare for men's] if she wasn't also making assumptions about air traffic controllers. "Thoughts about sex enter women's brains once every couple of days; for men, thoughts about sex occur every minute."

Has she not seen Sex and the City?

In a thoroughly researched series of posts, Mark Liberman explains that there's no evidence at all for the claim that

I looked through the book to try to find the research behind the 20,000-vs.-7,000-words-per-day claim, and I looked on the web as well, but I haven't been able to find it yet. Brizendine also claims that women speak twice as fast as men (250 words per minute vs. 125 words per minute). These are striking assertions from an eminent scientist, with big quantitative differences confirming the standard stereotype about those gabby women and us laconic guys. The only trouble is, I'm pretty sure that both claims are false.

The main goal of this functional magnetic resonance imaging (fMRI) study was to identify the neural correlates of a mystical experience. The brain activity of Carmelite nuns was measured while they were subjectively in a state of union with God. This state was associated with significant loci of activation in the right medial orbitofrontal cortex, right middle temporal cortex, right inferior and superior parietal lobules, right caudate, left medial prefrontal cortex, left anterior cingulate cortex, left inferior parietal lobule, left insula, left caudate, and left brainstem. Other loci of activation were seen in the extra-striate visual cortex. These results suggest that mystical experiences are mediated by several brain regions and systems.

The activation conditions compared in the figure above are the Mystical condition, in which subjects were asked to remember and relive (eyes closed) the most intense mystical experience ever felt in their lives as a member of the Carmelite Order vs. the Baseline condition, which was the "resting state" with eyes closed.

Mystical experience is characterized by a sense of union with God. It can also include a number of other elements, such as the sense of having touched the ultimate ground of reality, the experience of timelessness and spacelessness, the sense of union with humankind and the universe, as well as feelings of positive affect, peace, joy and unconditional love.

However, the experiment did not involve direct induction of a "mystical experience," but rather a memory of one. Importantly, the Control condition asked the nuns to remember and relive (eyes closed) the most intense state of union with another human ever felt in their lives while being affiliated with the Carmelite Order. So the important contrast is "remember union with God" (Mystical) vs. "remember union with human" (Control). Here's the list of brain areas more active in the former:

Nonetheless, the brain regions activated by both Mystical and Control conditions (each compared to Baseline) were right superior parietal lobule, left caudate, left ACC, and left brainstem. Interestingly,

The average intensity of the subjective experience was 3.06 ± 0.93 (range: 2–5) during the Mystical condition and 3.04 ± 0.80 (range: 2–5) during the Control condition.

After the scan, the nuns rated the intensity of the subjective experience during the Control and Mystical conditions using a rating scale ranging from 0 (no experience of union) to 5 (most intense experience of union ever felt). This was a rating of how they actually felt during the scan, not how they felt during the original episode (recalled to elicit the Control and Mystical states). So during the scan, the nuns felt equally intense about remembering "union with God" and "union with human." During the Mystical condition, the nuns reported feeling the presence of God, unconditional and infinite love, plenitude, and peace. They also reported feeling unconditional love during the Control condition.

Also interestingly, the caudate and ACC regions activated in both these conditions (and hence subtracted away in the direct comparison between them) are ALSO quite active when an amorous lover views a photo of his/her romantic partner (Bartels & Zeki, 2000; Aron et al., 2005; Fisher et al., 2005). BUT it's not up to me to engage in reverse inference1 here...

Antidepressants are assumed to work on the specific neurobiology of depressive disorders according to a "disease-centred" model of drug action. However, little evidence supports this idea. An alternative, "drug-centred," model suggests that psychotropic drugs create abnormal states that may coincidentally relieve symptoms. Drug-induced effects of antidepressants vary widely according to their chemical class—from sedation and cognitive impairment to mild stimulation and occasionally frank agitation. Results of clinical trials may be explained by drug-induced effects and placebo amplification. No evidence shows that antidepressants or any other drugs produce long-term elevation of mood or other effects that are particularly useful in treating depression.

The essay's argument is incoherent and relies entirely on the following analogy:

Alcohol can relieve symptoms of social phobia, but this does not mean that alcohol corrects a chemical imbalance underlying social phobia.

The authors skip right over their (unstated) assumption that depression has nothing to do with the brain. Hmm, so moods and thoughts are not caused by the brain? Perhaps they are caused by "spooky stuff" -- Cartesian souls or spirits that exist in the ether somewhere.The last sentence of the essay:

We have proposed an alternative drug-centred model of drug action that is consistent with a demedicalised approach to depression.

Um, no they haven't. They gave absolutely no evidence that we should abandon a disease-centered model of psychotropic drug action. It's not clear how antidepressants work, true, but that doesn't mean they're useless. And the concept of "demedicalization" isn't mentioned until that final sentence.

...abandoning the disease-centred model of antidepressant action squarely challenges the notion of depression as a biologically based medical disease. The argument presented here supports claims that the medical concept of depression obscures the diversity of problems and experiences that come to be so labelled, and that social explanations and interventions have been undervalued.

That statement about social explanations came out of the blue. But you can read all about it here:

Moncrieff J. (2006). Psychiatric drug promotion and the politics of neo-liberalism. Br J Psychiatry 188:301-2. The pharmaceutical industry has popularized the idea that many problems are caused by imbalances in brain chemicals. This message helps to further the aims of neo-liberal economic and social policies by breeding feelings of inadequacy and anxiety. These feelings in turn drive increasing consumption, encourage people to accept more pressured working conditions and inhibit social and political responses.

Sure, overpromotion of psychiatric drugs is bad, the history of psychiatry is littered with many instances of abuse, and really, I'm left-wing and anti-consumption, but... this whole line of reasoning is like creationism, but in the guise of progressive political thought.

About Me

Born in West Virginia in 1980, The Neurocritic embarked upon a roadtrip across America at the age of thirteen with his mother. She abandoned him when they reached San Francisco and The Neurocritic descended into a spiral of drug abuse and prostitution. At fifteen, The Neurocritic's psychiatrist encouraged him to start writing as a form of therapy.